With Wednesday's privacy policy revision (and the unsaid truth that if users take no action their updates will be posted for the entire Internet to see) Facebook may be opening the door to its own downfall.

When the site was founded, it brought users with preexisting offline connections together – initially just colleges, then companies, high schools, and regions.

As it announced it would last week, today Facebook did away with regional networks. And If they haven't already, all 350 million of the site's users will soon see a dialog box that will require them to review the site's new privacy controls and use a "transition tool" to help translate their current privacy settings into terms that mesh with the new policy.

What's changed? And why?

In addition to the demise of regional networks, Facebook today introduced more "granular" controls on what information is shared and with whom. Functions like photos or status updates may be set to post only to specific users, just friends, friends of friends, or to everyone, which is now the default setting. And "everyone" now means not just all of Facebook, but the public Web as well. In a sense, Facebook is clearing out its 'walled garden' and making users ask to move back inside.

In the days since Facebook's founding, the success of Twitter has created massive interest in real-time search. Twitter was the go-to search engine for people looking for information on the death of Michael Jackson, the crash of a US Airways jet into the Hudson, and other recent breaking news stories. Facebook sees millions of similar posts fly across its site everyday and wants to bring its gargantuan user base to the party. But throwing the switch to public without very clearly telling its users could be a recipe for disaster.

There's no manual on "How to use Facebook," (unless David Pogue has written one) but most Facebookers' posts are much more personal – and relevant to a smaller group – than what they'd share on Twitter. Maybe it has to do with the fact that Facebook profiles are linked to a name and Twitter to a made-up handle. But the difference is there. And as the Web saw with Beacon, the program launched in 2007 that saw Facebook users' external activity posted to their news feeds without a lot of notification ahead of time, to try to capitalize on the exchange of Facebook updates is dangerous ground.

Likewise, though real-time searchable updates from a mass of Facebook users sounds appealing, will those users take kindly to the idea of their personal posts being broadcast across the Web?

Facebook is making a big deal of making sure users know how to take control of their privacy. But as Wired reports, 80 to 85 percent of users haven't bothered to adjust their current settings, so will an easier to understand interface really make much of a difference?

The increased focus on privacy will do one of two things: Either it will cause a sizable chunk of users to batten down the hatches, protecting their updates from all but their closest online acquaintances (not good for Facebook's vision of real-time search), or it will fly by users unnoticed, letting the default setting reign and sharing everything. This is good for Facebook, and the user, until a friend points out that their family vacation photos are, say, on the first page of a Google image search for "Hawaii." Either way, the site could suffer.

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